Google has ~900 fonts available for use in Google Documents and Google Slides.
These can be browsed at https://fonts.google.com.
This video below from :00 to 2:35 shows you exactly how to access these additional fonts.
There are many fonts for fun and variety, but there two are notable for accessibility reasons:
Lexend is designed for students confronting reading difficulties. Research proves this font makes a difference.
Atkinson Hyperlegible is designed for people with vision issues and is available from Google.
